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| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2019-03-05 11:30:02 +0100 |
|---|---|---|
| committer | Christian Borntraeger <borntraeger@de.ibm.com> | 2019-04-26 09:08:17 +0200 |
| commit | 8b905d28ee17795c939813b2f6947829774619b9 (patch) | |
| tree | 1926b9c6429067d79b898fedce16e7139a95f3ab /arch/s390/kvm/kvm-s390.c | |
| parent | KVM: polling: add architecture backend to disable polling (diff) | |
| download | linux-8b905d28ee17795c939813b2f6947829774619b9.tar.xz linux-8b905d28ee17795c939813b2f6947829774619b9.zip | |
KVM: s390: provide kvm_arch_no_poll function
We do track the current steal time of the host CPUs. Let us use
this value to disable halt polling if the steal time goes beyond
a configured value.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Diffstat (limited to '')
| -rw-r--r-- | arch/s390/kvm/kvm-s390.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index eb68ada1334b..ed280a4fea07 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -75,6 +75,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = { { "halt_successful_poll", VCPU_STAT(halt_successful_poll) }, { "halt_attempted_poll", VCPU_STAT(halt_attempted_poll) }, { "halt_poll_invalid", VCPU_STAT(halt_poll_invalid) }, + { "halt_no_poll_steal", VCPU_STAT(halt_no_poll_steal) }, { "halt_wakeup", VCPU_STAT(halt_wakeup) }, { "instruction_lctlg", VCPU_STAT(instruction_lctlg) }, { "instruction_lctl", VCPU_STAT(instruction_lctl) }, @@ -177,6 +178,11 @@ static int hpage; module_param(hpage, int, 0444); MODULE_PARM_DESC(hpage, "1m huge page backing support"); +/* maximum percentage of steal time for polling. >100 is treated like 100 */ +static u8 halt_poll_max_steal = 10; +module_param(halt_poll_max_steal, byte, 0644); +MODULE_PARM_DESC(hpage, "Maximum percentage of steal time to allow polling"); + /* * For now we handle at most 16 double words as this is what the s390 base * kernel handles and stores in the prefix page. If we ever need to go beyond @@ -3166,6 +3172,17 @@ static void kvm_gmap_notifier(struct gmap *gmap, unsigned long start, } } +bool kvm_arch_no_poll(struct kvm_vcpu *vcpu) +{ + /* do not poll with more than halt_poll_max_steal percent of steal time */ + if (S390_lowcore.avg_steal_timer * 100 / (TICK_USEC << 12) >= + halt_poll_max_steal) { + vcpu->stat.halt_no_poll_steal++; + return true; + } + return false; +} + int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu) { /* kvm common code refers to this, but never calls it */ |